Nuts, seeds and legumesf14

Soy allergy

Soy allergy comes in two forms: in children as a common food allergy, and in adults with birch allergy as cross-reactivity. Soy drinks and protein powder can then cause unexpectedly strong reactions.

Allergen
Soy Glycine max
Allergen code
f14
Key allergens
Gly m 4, Gly m 5, Gly m 6
Included in
1 test
Contents
  1. What is soy allergy?
  2. Symptoms
  3. Where soy is found
  4. Cross-reactivity
  5. How to get tested
  6. Frequently asked questions

What is soy allergy?

Soy is a legume that is used in more and more foods. In young children, soy allergy is one of the common food allergies, and many outgrow it.

In adults in northern and central Europe, soy allergy is often due to birch allergy. The protein Gly m 4 in soy resembles Bet v 1 in birch pollen. People who drink a soy drink or a protein shake, or eat larger amounts of lightly processed soy, can then get stronger reactions than with ordinary cross-reactivity – with swelling in the mouth and throat, hives and sometimes breathing difficulties.

The storage proteins Gly m 5 and Gly m 6 withstand heat and can cause allergic reactions independently of pollen.

Symptoms

  • Itching and swelling in the mouth, lips and throat
  • Hives
  • Stomach problems
  • Breathing difficulties and, in rare cases, anaphylaxis

Where soy is found

Soy is found in soy drinks, tofu, tempeh, soy sauce, vegetarian products, protein powder, bread, biscuits and processed meats. Soy lecithin and refined soybean oil contain very little protein. Soy is one of the allergens that must always be declared on the ingredients list.

Cross-reactivity

Besides birch pollen, soy can cross-react with other legumes such as peanut, peas and lupin. A positive blood test does not mean that you react to all of them.

How to get tested

Soy (allergen code f14) is included in our Sesame, soya and mustard allergy test. The test shows whether you have IgE antibodies to soybean.

Frequently asked questions

Why do I react to soy drinks but not to soy sauce?

Soy sauce is fermented and heavily processed, and the amount of soy is small. Soy drinks contain a lot of lightly processed soy protein and are drunk quickly in large amounts, which can cause reactions in people with birch allergy.

Is soy lecithin dangerous if I am allergic to soy?

Soy lecithin contains very little protein, and most people with soy allergy tolerate it. Talk to your doctor if you have had severe reactions.

Often cross-reacts with

This text is general information and does not replace an assessment by a healthcare professional. In an emergency, call 112. If you have questions about your health, contact your doctor.

Tests for soy allergy

You take the sample yourself at home. The tests measure IgE antibodies in a capillary blood sample.

Nuts, seeds and legumes

Peanut, hazelnut, sesame, soy and mustard are among the 14 allergens that must always be declared on the ingredients list. In adults with birch allergy, reactions are often due to cross-reactivity.

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